When we look for the first Europeans to cross the Atlantic we need to take a good look at the stepping stones they used to get here. One could be the ice in the northern Atlantic. I feel when you step on a rock to cross a creek you will leave a mark on the bridge stone. To show a likely stone in the Atlantic which may have many marks in the form of runic letters is the Axores.
The following link is a good history of the Azores and the mix of the early setlers to claim it as home. It is likely they had to develope a common alphebet to identify their dead or mark property boundaries. They likely used runes and may have added the hooked X because they all became under the The Knights of Christ faith.
It is a good history of the Azores and may give us a connection to additional ground work needed about this stepping stone.
I have sent an email to Dr. DaSilva,s wife in hopes to obtain a Azore contact. Any help would be great.